Re: PATA drivers in libata?

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Sun, 2005-02-13 at 13:51 -0500, Jeff Garzik wrote:
> I wanted to open a discussion on libata and PATA.
> 
> libata-dev now has two drivers that support PATA, pata_pdc2027x and 
> ata_piix, and the core is getting close (DMA blacklist in, C/H/S support 
> close).
> 
> What are the opinions on issues relating to making PATA libata support 
> available in the upstream kernel?  Here's my random list.
> 
> * I think CONFIG_IDE should continue to be the default answer for "what 
> driver do I use for PATA?"

Yes.

> * Should there be a config option similar to CONFIG_BLK_DEV_IDE_SATA, 
> called CONFIG_SCSI_ATA_PATA?  A runtime 'pata' module option?  Should we 
> include 'DANGER DANGER conflicts with CONFIG_IDE' in the Kconfig 
> description?

Eventually... I'm thinking I may port the "macio" IDE to libata one day,
but for now, I still need both drivers/ide for it and libata for SATA.

> * With ATA passthru (in libata-dev currently), libata supports SMART and 
> the HDIO_CMD/HDIO_TASK generalized ioctls.  Should I care about 
> supporting other ioctls?
> 
> * pci_enable_device() issues?
> 
> * power management differences?

Well, libata doesn't have power management proper at all for now. In
fact, I need to do something at the generic SCSI level similar to what I
did for drivers/ide, that is turning the PM callbacks into requests down
the queues etc... but I don't have any SCSI or libata HW that can power
manage at the moment, so I didn't quite bother yet.

(Though if I ported "macio" IDE ... )

Ultimately, it will have to be done for things like USB & firewire too
anyway. So maybe I should start working on this soonish. I talked a bit
with jejb at OLS a year or 2 ago about the way to do it, it shouldn't be
that much different than what I do in drivers/ide, but then, I know
pretty much nothing about the linux scsi layer...

Ben.